#!/bin/bash

# A script to delete the multi-tier VPC resources created by create_multi_tier_vpc.sh.

# --- Configuration ---
REGION="us-east-1"
VPC_NAME="MyWebAppVPC" # Must match the name used in create_multi_tier_vpc.sh

# --- Helper function to get resource ID by tag ---
get_resource_id_by_tag() {
  local resource_type=$1
  local tag_name=$2
  local tag_value=$3
  aws ec2 describe-$resource_type \
    --filters "Name=tag:$tag_name,Values=$tag_value" \
    --region $REGION \
    --query "$resource_type[0].$resource_type_id_field" \
    --output text
}

# --- Get IDs of created resources ---
echo "--- Retrieving IDs of resources to delete ---"
VPC_ID=$(aws ec2 describe-vpcs --filters "Name=tag:Name,Values=$VPC_NAME" --region $REGION --query 'Vpcs[0].VpcId' --output text)
if [ -z "$VPC_ID" ]; then echo "VPC '$VPC_NAME' not found. Exiting."; exit 0; fi
echo "Found VPC ID: $VPC_ID"

PUBLIC_SUBNET_ID=$(aws ec2 describe-subnets --filters "Name=tag:Name,Values=${VPC_NAME}-Public-Subnet" --region $REGION --query 'Subnets[0].SubnetId' --output text)
PRIVATE_SUBNET_APP_ID=$(aws ec2 describe-subnets --filters "Name=tag:Name,Values=${VPC_NAME}-Private-App-Subnet" --region $REGION --query 'Subnets[0].SubnetId' --output text)
PRIVATE_SUBNET_DB_ID=$(aws ec2 describe-subnets --filters "Name=tag:Name,Values=${VPC_NAME}-Private-DB-Subnet" --region $REGION --query 'Subnets[0].SubnetId' --output text)

IGW_ID=$(aws ec2 describe-internet-gateways --filters "Name=tag:Name,Values=${VPC_NAME}-IGW" --region $REGION --query 'InternetGateways[0].InternetGatewayId' --output text)
NAT_GW_ID=$(aws ec2 describe-nat-gateways --filters "Name=tag:Name,Values=${VPC_NAME}-NAT-GW" --region $REGION --query 'NatGateways[0].NatGatewayId' --output text)
EIP_ALLOC_ID=$(aws ec2 describe-nat-gateways --filters "Name=tag:Name,Values=${VPC_NAME}-NAT-GW" --region $REGION --query 'NatGateways[0].NatGatewayAddresses[0].AllocationId' --output text)

PUBLIC_RT_ID=$(aws ec2 describe-route-tables --filters "Name=tag:Name,Values=${VPC_NAME}-Public-RT" --region $REGION --query 'RouteTables[0].RouteTableId' --output text)
PRIVATE_RT_ID=$(aws ec2 describe-route-tables --filters "Name=tag:Name,Values=${VPC_NAME}-Private-RT" --region $REGION --query 'RouteTables[0].RouteTableId' --output text)

WEB_SG_ID=$(aws ec2 describe-security-groups --filters "Name=group-name,Values=${VPC_NAME}-Web-SG" --region $REGION --query 'SecurityGroups[0].GroupId' --output text)
APP_SG_ID=$(aws ec2 describe-security-groups --filters "Name=group-name,Values=${VPC_NAME}-App-SG" --region $REGION --query 'SecurityGroups[0].GroupId' --output text)
DB_SG_ID=$(aws ec2 describe-security-groups --filters "Name=group-name,Values=${VPC_NAME}-DB-SG" --region $REGION --query 'SecurityGroups[0].GroupId' --output text)

echo "--- Starting cleanup of VPC resources ---"

# --- Delete Security Groups ---
echo "Deleting Security Groups..."
[ -n "$WEB_SG_ID" ] && aws ec2 delete-security-group --group-id $WEB_SG_ID --region $REGION && echo "Deleted Web SG: $WEB_SG_ID"
[ -n "$APP_SG_ID" ] && aws ec2 delete-security-group --group-id $APP_SG_ID --region $REGION && echo "Deleted App SG: $APP_SG_ID"
[ -n "$DB_SG_ID" ] && aws ec2 delete-security-group --group-id $DB_SG_ID --region $REGION && echo "Deleted DB SG: $DB_SG_ID"
sleep 5 # Give time for SGs to detach

# --- Delete Route Table Associations and Routes ---
echo "Deleting Route Table Associations and Routes..."
# Disassociate public route table from public subnet
[ -n "$PUBLIC_RT_ID" ] && [ -n "$PUBLIC_SUBNET_ID" ] && \
  ASSOC_ID=$(aws ec2 describe-route-tables --route-table-ids $PUBLIC_RT_ID --region $REGION --query "RouteTables[0].Associations[?SubnetId=='$PUBLIC_SUBNET_ID'].RouteTableAssociationId" --output text) && \
  [ -n "$ASSOC_ID" ] && aws ec2 disassociate-route-table --association-id $ASSOC_ID --region $REGION

# Delete routes from public route table
[ -n "$PUBLIC_RT_ID" ] && aws ec2 delete-route --route-table-id $PUBLIC_RT_ID --destination-cidr-block 0.0.0.0/0 --region $REGION

# Disassociate private route table from private subnets
[ -n "$PRIVATE_RT_ID" ] && [ -n "$PRIVATE_SUBNET_APP_ID" ] && \
  ASSOC_ID=$(aws ec2 describe-route-tables --route-table-ids $PRIVATE_RT_ID --region $REGION --query "RouteTables[0].Associations[?SubnetId=='$PRIVATE_SUBNET_APP_ID'].RouteTableAssociationId" --output text) && \
  [ -n "$ASSOC_ID" ] && aws ec2 disassociate-route-table --association-id $ASSOC_ID --region $REGION
[ -n "$PRIVATE_RT_ID" ] && [ -n "$PRIVATE_SUBNET_DB_ID" ] && \
  ASSOC_ID=$(aws ec2 describe-route-tables --route-table-ids $PRIVATE_RT_ID --region $REGION --query "RouteTables[0].Associations[?SubnetId=='$PRIVATE_SUBNET_DB_ID'].RouteTableAssociationId" --output text) && \
  [ -n "$ASSOC_ID" ] && aws ec2 disassociate-route-table --association-id $ASSOC_ID --region $REGION

# Delete routes from private route table
[ -n "$PRIVATE_RT_ID" ] && aws ec2 delete-route --route-table-id $PRIVATE_RT_ID --destination-cidr-block 0.0.0.0/0 --region $REGION

# Delete Route Tables
[ -n "$PUBLIC_RT_ID" ] && aws ec2 delete-route-table --route-table-id $PUBLIC_RT_ID --region $REGION && echo "Deleted Public RT: $PUBLIC_RT_ID"
[ -n "$PRIVATE_RT_ID" ] && aws ec2 delete-route-table --route-table-id $PRIVATE_RT_ID --region $REGION && echo "Deleted Private RT: $PRIVATE_RT_ID"
sleep 5

# --- Delete NAT Gateway ---
echo "Deleting NAT Gateway..."
[ -n "$NAT_GW_ID" ] && aws ec2 delete-nat-gateway --nat-gateway-id $NAT_GW_ID --region $REGION && echo "Deleted NAT GW: $NAT_GW_ID"
[ -n "$NAT_GW_ID" ] && aws ec2 wait nat-gateway-deleted --nat-gateway-ids $NAT_GW_ID --region $REGION
[ -n "$EIP_ALLOC_ID" ] && aws ec2 release-address --allocation-id $EIP_ALLOC_ID --region $REGION && echo "Released EIP: $EIP_ALLOC_ID"
sleep 5

# --- Detach and Delete Internet Gateway ---
echo "Detaching and deleting Internet Gateway..."
[ -n "$IGW_ID" ] && aws ec2 detach-internet-gateway --internet-gateway-id $IGW_ID --vpc-id $VPC_ID --region $REGION
[ -n "$IGW_ID" ] && aws ec2 delete-internet-gateway --internet-gateway-id $IGW_ID --region $REGION && echo "Deleted IGW: $IGW_ID"
sleep 5

# --- Delete Subnets ---
echo "Deleting Subnets..."
[ -n "$PUBLIC_SUBNET_ID" ] && aws ec2 delete-subnet --subnet-id $PUBLIC_SUBNET_ID --region $REGION && echo "Deleted Public Subnet: $PUBLIC_SUBNET_ID"
[ -n "$PRIVATE_SUBNET_APP_ID" ] && aws ec2 delete-subnet --subnet-id $PRIVATE_SUBNET_APP_ID --region $REGION && echo "Deleted Private App Subnet: $PRIVATE_SUBNET_APP_ID"
[ -n "$PRIVATE_SUBNET_DB_ID" ] && aws ec2 delete-subnet --subnet-id $PRIVATE_SUBNET_DB_ID --region $REGION && echo "Deleted Private DB Subnet: $PRIVATE_SUBNET_DB_ID"
sleep 5

# --- Delete VPC ---
echo "Deleting VPC..."
[ -n "$VPC_ID" ] && aws ec2 delete-vpc --vpc-id $VPC_ID --region $REGION && echo "Deleted VPC: $VPC_ID"

echo -e "\n--- VPC cleanup complete! ---"